Image Quality - Analog, Digital, DVD
In the February preview, we note the differences between Analog, Digital, HDTV and DVD. Essentially, Standard Analog Television is based on a 480i configuration, comprised of 480 vertically interlaced lines. The other common designation is 480p, where the vertical lines are drawn on the screen at one time, known as progressive scan. This is commonly referred to as Digital Signal and offers similar quality to that of a DVD. High Definition Television Signal, on the other hand, is base on a 720p or 1080i format. The 720p format is a 1280x720 progressive scan image where as the 1080i format displays an interlaced image at 1920x1080. Additionally, the signal is capable of carrying more audio information, including multiple tracks, offering Dolby digital surround sound quality. This also gives programmers the option to send secondary channels that can display additional data such as programming data, news and weather along with regular programming.
Below we've included some image comparisons to demonstrate the various differences in image quality. To start we are going to compare Analog television signal to digital. We took both analog images at their native 720x480 and overlayed a 400% zoomed section to see image quality up close. We then took the digital equivalents of these images at their native 1920x1080 and did the same procedure. We then resized the images to reduce file size and download times, but you can still get the idea even after resizing and image compression was applied.
|Analog Image #1
||Analog Image #2
|Digital Image #1
||Digital Image #2
The first thing we noticed is how with the digital images the entire screen is used, whereas the analog equivalents have unused space at the top and bottom of the screen. From there we took a closer look at each image and even in there thumbnail views the quality difference is obvious. The images on the left shows a much more defined collar and facial features in the digital format, where the analog is fuzzy and the details of the collar are muted. The image series on the right demonstrate similar differences. The analog image is also fuzzy and the lines of the image are less defined than the digital equivalent. The digital image shows a far more sharp image, with clean, crisp detail even when zoomed in.
Next, we used some photos to demonstrate the advantages of a 1920x1080i digital image over a 720x480 DVD image. Each image is a close up of a section of the screen showing the detail differences of each. Each image is zoomed in 400% and compared. When you compare the top two images the details are not immediately apparent, but once you take a moment to "read" them, the quality becomes more obvious. The first was a slight difference in aspect ratio between the two with the DVD image having a more elongated appearance. When we take a closer look at the face and arm of "Clarice" we see a greater amount of detail and clarity with the digital image. The edges of her face and wounds are more detailed, suffering less loss when zoomed in.
|DVD Image #1||Digital Image #1|
|DVD Image #2||Digital Image #2|
The second series of images is a close up of Anthony Hopkins. Here the details of his face are clearer and more pronounced with the digital images on the right with a more natural appearance. His suit lines are clearer as well and the difference in the details of his tie are obvious, even in the thumbnail view.